Telephone selector switch utilizing odd-even relay



April 1953 V R. F. STEHLlK 2,635,147

TELEPHONE SELECTOR SWITCH UTILIZING ODD-EVEN RELAY Filed 001;. 25, 19484 Sheets-Sheet l 625 FIG.9

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TELEPHONE SELECTOR SWITCH UTILIZING ODD-EVEN RELAY RUDOLPH F. STEHLIKATTORNEY April 14, 1953 Filed Oct. 25. 1948 R. F. STEHLIK 2,635,147

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J68 769 r INVENTOR.

I RUDOLPH F. STEHLIK u l8l9 3| sue 5| sass 1| 11119191 9 92 a I I0 3% 50 10 I FIG.7A

v i ATTORNEY Patented Apr. 14, 1953 TELEPHONE SELECTOR SWITCH UTILIZINGODD-EVEN RELAY Rudolph Frank Stehlik, Antwerp, Belgium, as-

signor to Automatic Electric Laboratories, Inc., Chicago, 111., acorporation of Delaware Application October 25, 1948, Serial N 0. 56,363

12 Claims.

This invention relates in general to telephone systems, and moreparticularly to automatic telephone systems employing switches of thesinglemotion rotary type, wherein one operating magnet is directivelycontrolled to position the related switch on desired bank contacts, andthe same magnet is later automatically controlled to return the switchto normal position.

It is an object of the invention to provide in a telephone system of thecharacter described, new and novel circuit means for accomplishing thevarious telephone connections.

Another object of the invention is to provide in a telephone system ofthe character described, a simplified and inexpensive switch trainwherein each switch utilizes two sets of wipers and associated bankcontact sets in a new and novel manner for extending calls from twogroups of lines to the next switch unit in the train.

A further object of the invention is to provide in a telephone system ofthe character described, an improved numerical switch which incorporatesa relay of the so-called odd-even type functioning responsive toreceived impulses of a digit in a new and novel manner for causing thepositioning of two sets of wipers according to the value of the receiveddigit, and for connecting the switch to one of the sets of wipers to theexclusion of the other set of wipers also according to the value of thereceived digit.

A feature of the invention resides in the novel arrangement whereby theodd-even relay of a numerical switch always remains in the restoredposition with its operating magnet drawing no current after the relayhas connected the switch to one or the other of the two sets of wipers.

Another feature of the invention is the provision of two sets of contactsprings on the oddeven relay of a numerical switch which are operatedand restored in the following novel manner. One of the two sets ofsprings is operated each time the magnet of the odd-even relay isenergized, and is always restored to normal position each time themagnet is de-energized; and the other set of springs is operated onlyupon the first de-energization of the magnet of the oddeven relay,remaining operated until and through the second energization of themagnet, and is restored to normal position only upon the secondde-energization of the magnet.

i A further feature of the invention relates to the use of anextra-control wiper and associated row of bank contacts in a numericalswitch cooperating with the functioning of the odd-even relay forcontrolling the operating magnet of the 2 switch in a new and novelmanner, whereby the two sets of wipers of the switch are automaticallykicked-off the home position of one group of bank contacts to the homeposition of another group of bank contacts.

An additional feature of the invention concerns the new and novel mannerin which the kickoff operation outlined in the preceding paragraphoccurs when the odd-even relay is in an even position (relay hasoperated and restored twice) while the next odd-numbered impulse of adialed digit is being received.

The various objects and features of the invention will be understoodbest from a perusal of the following detailed description of thedrawings comprising Figures 1 to 9, inclusive, which show by means ofthe usual circuit diagrams a sufficient amount of apparatus to enablethe invention to be described and understood.

Figure l is a simple diagram illustrating the elements of the inventionas applied to a station system.

Figure 2 shows the numbering and grouping of the bank contact setsassociated with the various switches.

Figure 3-A shows a telephone station connected in multiple to therespective bank contact sets in even-tens groups of the line-finderswitches and the connector switches.

Figure 3-B shows a telephone station connected in multiple to therespective bank contacts sets in odd-tens groups of the line-finderswitches and the connector switches.

Figure 4 shows the relays and switch of the allotter which assignsline-finder switches to find calling lines.

Figure 5 shows one of the line-finder switches equipped with odd andeven sets of wipers and associated banks.

Figure 6 shows a selector switch equipped with odd and even sets ofwipers and associated banks and, in addition, an extra-control wiper andassociated bank.

Figure 6-A shows the wiring of the contacts of the extra-control bankassociated with each selector switch. The extra-control tank isindividual to each selector switch and, therefore, its contacts are notmultip-led to other selector switch extracontrol banks.

Figure 7 shows a connector switch equipped with odd and even sets ofwipers and associated banks and, in addition, an extra-control wiper andassociated bank.

Figure 'Z-A shows the wiring or" the contacts of the extra-control bankassociated with each connector switch. The extra-control bank isindividual to each connector switch and, therefore, its contacts are notmultipled to other connector switch extra-control banks.

Figure 8 shows the elements of the invention as applied to a telephonesystem of 1,000 stations.

Figure 9 is a simplified diagram illustrating the various wiper Steppingcircuits of the selector switch shown in Figure 6.

Referring now to Figure 1, the telephone exchange shown therein consistsessentially of 100 telephone stations indicated at and E05, and a numberof finder-connector links, such as H0, interconnected to form a completesystem. Each finder-connector link comprises a finder switch, such as II5, and a connector switch, such as I20. The finder switch H comprises arelay group H6, an odd-tens wiper Ill and associated bank of five groupsof ten sets of contacts each, and an even-tens wiper H8 and associatedbank of five groups of ten sets of contacts each. The connector switchI20 comp-rises a relay group I21, an odd-tens wiper I23 and associatedbank of five groups of ten sets of contacts each, and an even-tens wiperI22 and associated bank of five groups of ten sets of contacts each. The100 lines connecting the telephone stations to the switches are dividedinto two main groups of 50 lines each, the lines of one 50-group beingconnected to the contact sets of the odd-numbered groups (I, 3, 5, 1 andS) of the line-finder and connector banks, and the lines of the other50-group to the contact sets of the even-numbered groups (2, 4, 6, 8 and0) of the line-finder and connector banks. Each sub-group of lines is,therefore, known as an odd-tens group or an even-tens group, dependingupon whether the 10 lines of the sub-group are connected to odd groupsor even groups of the mentioned bank contacts.

Referring now to Figure 8, the telephone exchange shown therein consistsessentially of 1000 telephone stations indicated at 80% and 305, aproper number of finder-selector links, such as 8I0, and a proper numberof connector switches, such as 825, all interconnected to form acomplete system. Each finder-selector link comprises a finder switch,such as M5, and a selector switch, such as 820. The finder switch 815comprises a relay group 8|6, an odd-tens wiper Bi! and associated bankof five groups of ten sets of contacts each, and an even-tens wiper 8H!and associated bank of five groups of ten sets of contacts each. Theselector switch 320 comprises a relay group BZI, an odd-tens wiper 82Sand associated bank of five groups of ten sets of contacts each, and aneven-tens wiper 822 and associated bank of five groups of ten sets ofcontacts each. The connector switch 825 comprises a relay group 825, anodd-tens wiper 821 and associated bank of five groups of ten sets ofcontacts each, and an even-tens wiper 828 and associated bank of fivegroups of ten sets of contacts each. The 1000 lines connecting thetelephone stations to the switches are divided into odd and even groupsof 500 lines each, the finder-selector links into 10 groups, and theconnector switches into 10 groups. Each group of finder-selector linksand a corresponding group of connector switches are associated with 50lines of the odd-numbered group of 500 lines and with 50 lines of theevennumbered group of 500 lines, the 50 odd-numbered lines beingconnected to the contact sets of the odd-numbered groups (I, 3, 5, l and9) of the line-finder and connector banks, and the 50 even-numberedlines being connected to the contact sets of the even-numbered groups(2, 4, 6, 8 and 0) of the line-finder and connector banks. Eachsub-group of 10 lines is, therefore, known as an odd-tens group or aneven-tens group, depending upon whether the 10 lines of the subgroup areconnected to odd groups or even groups of the mentioned finder andconnector bank contact sets. Five groups of the connector switches areconnected to the contact sets of the oddnumbered groups (R, 3, 5, I and9) of the selector switch banks, and the other five groups of theconnector switches to the contact sets of the even-numbered groups (2,t, 6, 8 and 0) of the selector switch banks. Each connector group is,therefore, known as an odd-tens group or an even-tens group, dependingupon whether the connector roup is connected to an odd group or an evengroup of the selector switch banks.

In a manner similar to that just described for a 1,000-station system,the invention can be applied equally as well to a 100,000-station systemor a 1,000,000-station system by the introduction of proper groups ofintermediate selector switches between the selector switch banks of thefinderselector links and the groups of connector switches.

Referring now to Figures 3-A and 3-3, a telephone substation isassociated with each of the telephone lines in the system, thesubstations A (Figure 3-A) and B (Figure 3-B) being respectivelyassociated with telephone lines 300 and 305. Each of the substations isprovided with a telephone instrument, a dial mechanism, and a ringer.Each telephone line includes a line relay and a cut-off relay, theserelays in line 300 being respectively indicated at 8!!) and 320, and inline 335 at 306 and 3 I 6.

The line-finder switches of the links and the allotter switch of theline-finder allotter are mechanically similar to well-known step-bysteprotary switches having no normal, or home, position, while the circuitsthereof have been altered in accordance with the present invention. Theline-finder switches of the links are each fitted with two sets ofwipers, two sets of banks, and two switching-through relays, as shown inFigure 5. The two sets of banks each comprise three rows of contactsdesignated and C respectively. One set of three rows of contacts isknown as the odd-tens set, and is further divided into five groups often contacts sets designated groups 1, 3, 5, '7, and 9, as shown in Fig.2. The other set of three rows of contacts is known as the even-tensset, and is further divided into five groups of ten contact setsdesignated groups, 2, 4, 6, 8 and 10; also as shown in Fig. 2. Thecontact sets of group 2 are in alignment with the contact sets of group1 so that as the oddtens wipers of the line-finder switch are passingover the contacts of group 1, the even-tens wipers are similarly passingover the contacts of group 2. The contact sets of group 4 are in similaralignment with the contact sets of group 3, the contact sets of group 6with the contact sets of group 5, etc.

The selector switch shown in Figure 6 is mechanically similar to theline-finder switch shown in Figure 5 with the general difference that itis directively controlled from a normal, or home, position by impulsesto select a particular group of bank contacts, and then automaticallyhunts in that group of bank contacts for a free outlet. Each selectorswitch is fitted with two sets of trunk wipers, one extra-control wiper,two sets of trunk banks and one extra-control bank. The two sets oftrunk banks each comprise three rows of contacts designated and Crespectively. The extra-control bank comprises one row of contactsdesignated extra-control, and is located between the two sets of trunkbanks. The arrangement and grouping of the seven rows of contacts isshown in Figure 2, it being appreciated thatthere are no individualextra-control contacts for the even- 2, 4, 6,?! 8H H0. extra-controlcontacts for the odd-tens groups 1, 3, 5, '7, and 9 also respectivelyserve for the even-tens groups 2, 4, 6, 8 and since the odd-tens andeven-tens groups are aligned in pairs in a manner similar to thatdescribed for the bank contacts of the line-finder switches.

The connector switch shown in Figure 7 is mechanically similar to theline-finder switch shown in Figure but instead of hunting for a markedpotential as the line-finder does, the connector is directivelycontrolled from a normal, or home, position by impulses. Each connectorswitch is fitted with two sets of line wipers, one extra-control wiper,two sets of line banks and one extra-control bank. The arrangement andgrouping of the seven rows of contacts is similar to that described inthe preceding paragraph for the selector switches with the generaldifierences that the word line is substituted for the word trunk, andthat the extra-control bank is fitted with an additional home contactlocated just to the left of contact ll of group 1 as shown in Figure7-A.

Both the selector switch (Figure 6) and the connector switch (Figure 7)in addition to being equipped with conventional type relays, are eachfitted with an odd-even type of relay for selecting either odd or evensets of wipers. One form of odd-even relay is described in theco-pending application Serial No. 30,555, filed June 2, 1948, to whichreference may be had for the mechanical and operating details of theodd-even relay. For the purposes of this specification, however, itshould suffice to understand that the sets of contact springs shownbelow the magnet of the odd-even relay in both Figures 6 and '7 areoperated each time the magnet is energized, and are always restored tonormal each time the magnet is de-energized; and that the contact springsets shown above the magnet of the oddeven relay in both Figures 6 and 7are operated only upon the first de-energization of the magnet,remaining operated until and through the. second energization of themagnet, and are restored to normal only upon the second de-energizationof the magnet. The cycle of operations is repeated as required.

Both the selector switch (Figure 6) and the connector switch (Figure 7)are each further equipped with a set of off-normal contact springs whichoperates when the wipers of the switch are stepped from their normalpositions, and which restores to normal when the switch wipers arereturned to their respective normal positions.

It should be understood at this time that while an embodiment of thepresent invention disclosed and described in this specification includesswitches having banks of 50 contact sets each, the invention is notlimited to the particular form shown but may utilize other bank-capacityswitches.

" It shouldbe further understood that while a plurality of batteryconnections are'shown in the drawings, they are preferably the samebattery. Also, in order to simplify the drawings further, relay contactsfor starting and stopping the operation of the tone and ringing currentgenerating equipment have been omitted. An X contact shown inassociation with a relay armature is a contact that makes or breaksbefore any other contacts of the particular relay are opened or closed,thus characterizing the relay as a two-step relay.

Having described the equipment and apparatus, a detailed description ofthe operation will now be given.

Calls in a ZOO-station system Briefly, calls are completed in thefollowing manner: The person at the calling station lifts the handsetfrom the telephone cradle and, after hearing conventional dial tone,dials the number of the desired station. If the called station is inuse, the calling person receives a busy tone. If the called station isnot busy, the called. station is rung automatically and intermittently.

. In order to describe a call in detail, it is assumed that station A(Fig. 3-A) desires to call station 13 (Fig. 3-B). It should beunderstood at this time that each link in the l00-station systemcomprises a line-finder switch, such as Figure 5, directly connected toa connector switch, such as Figure 7, by means of conductors, such as555, 552, 553, NH, 102 and H33. It should also be understood at thistime that the functions of connector switch, Figure 7, relating to dialtone, busy back, ringing the called line and the like are typical forexplanatory purposes only, and that this invention can be appliedequally as well to any of the many well-known connector switch circuits.The selector switch, Figure 6, is not included in the IOU-stationsystem. Responsive to the lifting of the handset from the telephonecradle at station A, a circuit for energizing line relay 3l0 iscompleted from ground, armature 322, lower conductor of line 399,telephone A, upper conductor of line 300, armature 32L upper winding ofline relay 3H] to battery. At armature 3H and working contact, linerelay 3lil marks station A as calling in the even-tens bank of thefinder switch acces sible to wiper 543 by connecting battery theretothrough the winding of cut-off relay 320 and the lower winding of linerelay 310 by way of conductor 3 33. At armature 3l2, line relay 3H)completes a circuit to start relay M9 (Fig. 4.) from ground, armatures323, 312, conductor SIS, winding of start relay M0 to battery, causingstart relay M6 to operate.

At armature 41 I, start relay All! connects the lower winding of relay420 to wiper 463: at armature M2, connects the upper winding of relay420 to wiper 465: at armature 4M, connects relay 430 to wiper 462; and,at armature M5, connects relay 435 to wiper 464. If either the odd-tensrelay 5H8 or the even-tens relay 520 of the finder switch now associatedwith the allotter (Figure 4) are in the operated position due to thefinder switch being inprior use, then relay 429 of the allotter willoperate through either its lower or upper winding (depending uponwhether ground is returned over conductor 413 or conductor 415). Acircuit is correspondingly completed to magnet 460 of the allotter fromground, armature 413 and working contact,-armature I and workingcontact, interrupter springs456, winding of magnet 46 !lto battery.Magnet 435 I accordingly self-drives wipers 43!435 in well known-mannerto the bank contactsof the next finder switch. If this finder switch isalso in prior use, relay 425 will remain operated and the circuit ofmagnet 459 is again completed at interrupter springs 4 66, the by tocause wiper 4 55 to h ad-v vancedto the next finder switch. Thisinteraction will continue until a free finder switch is found, whereuponrelay 425 will restore and, disable the circuit of magnet 453 atarmature 42!, thereby preventing further advancement of wipers 46 !455.As long as busy finder switches are tested, either relay 435 or relay435 may correspondingly operate, but since neither relay 435 nor relay435 directly control circuits when relay 425 is in the non-operatedposition, no circuits would be completed or disabled.

Assuming now that the finder switch of Figure 5 hasbeen selected byallotter Figure 4 and that this finder switch is in the idle position,then relay 425 restores and completes a circuit to relay 425 fromground, armature 4 i 3 and working contact, armature 42! and restingcontact, winding of relay 425 to battery, causing relay 425 to operate.Assuming further that the odd-tens wipers and the even-tens wipers ofthe finder .switch are standing on the bank contacts of line circuitsnot in use (idle), then a circuit is completed for relay 430 fromground, armature and resting contact (Figure 3-13) conductor bankcontact, wiper 533, conductor 4l2, bank contact, wiper 452, armature4H1, winding of relay 433 to battery; and a circuit is completed ,forrelay 435 from ground, armature 3H and resting contact (Figure 3-A),conductor 343, bank contact, wiper 543, conductor 4274, bank contact,wiper 454, armature 4|5, winding of relay 435 to battery. Both relays433 and 435 correspondingly operate, and a circuit is completed formagnet 545 of the finder switch from ground, armatures 429, 43!, 435,442, 452, wiper 45!, bank contact, conductor 41!, interrupter armature544, winding of magnet 54!) to battery. Magnet 543 accordinglyself-drives wipers 53!, 552, 533, 54!, 542 and 543 in well-known manneras long as either wiper 533 or wiper 543 find ground on the bankcontacts of tested line circuits.

When control wiper .543 of the line-finder connects with the bankcontact associated with conductor 343 (station A) battery throughwindings of cut-off relay 325 and line relay 3), armature 3!! andworking contact shunts down relay 435 causing relay 435 to open thecircuit of magnet 54!) at armature 435, thereby stopping wipers 54!, 542and 543 on the bank contacts connected to line circuit 335. Therestoration of relay 435 completes a circuit for relay 455 from ground,armatures 424, 437, 443, winding of relay 450 to battery, causing relay450 to operate and lock to ground by way of armatures 443, 453 and 424.At armature 45!, relay 45!! connects ground to conductor 475 of thefinder switch by way of armature 42! and working contact, wiper 465 andbank contact, thereby to operate even-tens relay 520 and cut-off relay325, the circuit for cut-off relay 320 being completed through armatures523 and 524. At armature 455, relay 45!] shunts start relay 4"], causingrelay 4'!) to restore-and open'the circuit of relay 425 at armature 4!3.Relay 425, however, is of the slow-torelease type and, therefore, doesnot restore immediately, but retains relay 45D operated for a shortinterval at armature 424. At armature 4544, relay 455 opens anotherpoint in the circuit to relay 443,,thereby to prevent the possibleoperation of relay 44! as long as relay 450 is operated. At, armature M3and resting contact, relay !!!i) completes a circuit to magnet 45!! ofthe allotter before relay 425 has had suflicient time to restore. Asrelay 425 restores, this last circuit to magnet 435 is opened atarmature 428, and magnet 455steps wipers 45i-465 of the allotter to thebank contacts of the next line-finder switch.

The operation ofeven-tens relay 520 of the line-finder connects wipers54!, 542 and 543 to conductors 55!, 552 and 553 leading to conductors15!, 152, and 753 of the connector switch (Figure 7) of the link by wayof armatures 52!, 522 and 523, thereby to seize the connector switch,and ground returned over conductors 103 and 553 from the connectorswitch is extended to eventens relay 525, wiper 543 and cut-ofi relay320 before relay 4-25 in the allotter restores and opens the circuit ofrelay 455. The ground from the connector switch to wiper 543 is extendedto the connector multiple bank contacts associated with conductor 343,thereby guarding telephone station A from intrusion.

Cut-ofi relay 7325, upon operating, disconnects the upper winding ofline relay 3 If) at armatures 32! and 322 to free the line fromattachments, but line relay 3H3 remains operated through its lowerwinding and the winding of cut-01f relay 325. t armature 323, cut-offrelay 320 removes ground from start relayv 455 of the finder-switchallotter, thereby freeing the finder-switch allotter from furthercontrol by'station A.

Should even-tens wipers 542, 542 and 543 have been standing on the "bankcontacts of line 305 when station A initiated the call, there would havebeen no rotation of the finder switch be cause battery through thewindings of cut-off relay 325 and line relay 3 ill would have beenimmediately connected to wiper 543. In that case relay 435 could notoperate, and the circuit for magnet 545 of the finder-switch wouldremain open at armature 435. At armature 431, relay 435 would completethe circuit for relay 455 from ground, armatures 424, 43?, 443, windingof relay 458 to battery, causing relay 450 to operate and lock to groundby way of armatures 443, 453 and 424. At armature 45!, relay 453 wouldconnect ground to conductor 4Y5 of the finder-switch by way of armature427i and working contact, wiper 465 and bank'contact, thereby to operateeventens relay 525 and cut-0E relay 32!), the circuit for cut-off relay325 being completed through armatures 523 and 524.

Line 350 of station A is connected to line relay I55 of thelinkconnector switch by way of conductors 55!, 552 and 'i!i2,'therebycausing relay 755 to operate. At armature 106 and working contact, relay755 completes the circuit to relay H5, causing relay iii to operate. Atarmature l! l, relay 7H5 returns ground to conductor Hi3 and conductor553 of the link finder switch. Dial tone is supplied to station A by wayof armature and resting contact, armature 743, armature 136 and restingcontact, condensers I34 and T51, conductor 75!, conductor 55!, armatime52!, wiper 54!, bank contact, and negative talking'conductor ofline"300'leading back to station Upon hearing the well-known dial tone,the calling person at station ,A dials the number of station B which, inthis instance, will be assumed to be digit 15. Responsive to thedialling of the digit 1, .thecircuit to line relay 105 of the connectorswitch is interrupted once, thereby causing relay I to restoremomentarily. At armature I06, relay I05 opens the circuit to relay H0,'but relay H5 is of the slow-to-release type and, therefore, does notrestore during this impulsing period. Consequently, the circuitscontrolled by relay Iii! are not disturbed. At armature I05 and restingcontact, relay I55 transmits an impulse to relay H5 in series withmagnet I50 of odd-even relay I00, causing relay II5 to operate andmagnet I50 to energize. This series circuit may be traced from ground byway of armature I06 and restin contact, armature H2 and working contact,armatures I33, I31, I24 and resting contact, I21, winding of relay 'II5,Wind- .ing of magnet I50 to battery. Armatures I55 and I56 are operatedresponsive to the energization of magnet I50 but perform no functions atthis time. Armatures I5 |-I54 of odd-even relay I03 do not operate uponthe energization of magnet I50. Relay I I 5 is of the slow to-releasetype and will, therefore, remain operated during this impulsing period.

Relay I05 r'eoperates upon the cessation of the impulse of the digit 1and, at armature I06, opens the series circuit through relay H5 andmagnet I50. Magnet I50 correspondingly deenergizes thereby to cause theoperation of armatures I5|-I54. Armature I54 completes a circuit fromground, armature I54 and working contact, armature I08 and workingcontact, armature I I I, armature I22 and resting contact, winding ofrelay I20 to battery, causing relay I26 to operate and lock to ground byway of armatures I23, I26 and I09. Relay H5 restores after a shortinterval.

-As previously explained, the groups 1 and 2 of the connector switchbanks are in alignment with each other, i. e., the first contact set ofgroup 1 is in alignment withthe first contact set of group 2, etc.Odd-tens wipers IBI, I62and I63 normally stand positioned just to theleft of group 1: wipers 11!, I12 and I13 normally stand positioned justto the left of group 2; and extra-control wiper I64 normally stands onthe H, or home, contact just to the left of the first contact (I I) of.group 1. It will, therefore, be readily seen that the impulse of thedialed digit 1 is not required to operate magnet I60 for the purpose ofadvancling wipers 'IBI, I62 and I63 to group 1, but is required forcausing one energization and one -de-energization of magnet I50 ofodd-even re- Ilay I60, thereby to select wipers TEL-I62 and I63 :at thetime relay H5 restores to normal and, at armature H9, prepares a pointin the circuit of relay I25. This action represents the tens digit (1)of the telephone number of station "B. It will also be observed that, atthis point of the operation, odd-even relay. N30 is in the restoredposition with magnet I58 drawingno current.

Responsive to the dialling of the units digit 5, the circuit to linerelay I05 of the connector switch is interrupted five times therebycausing relay 105 to be de-energizedgfive times. Relay 165, therefore,restores'momentarily for each impulse and, at armature I06, opens thecircuit to relay H0. Relay I I0, however, is of the slow-to-release typeand, therefore, does not restore during this impulsing period.Consequently the c u s contro ed by relay 110 .are

not disturbed. At armature I06 and resting contact, relay "15 transmitsan impulse to relay I25 in series with magnet for each de-energization.This series conduit may be traced from ground, armature I06 and restingcontact, armature I I 2 and working contact, armatures I33, I31, I24 andworking contact I I 9, winding of relay I25, winding of magnet I60 tobattery. Relay I25 operates with the first impulse of the digit 5 and,at armature I28, completes a series circuit through relay I25 and I60for the remaining four impulses of the digit 5. At armature I26, relayI25 opens the locking circuit of relay 12%, causing relay I20 torestore. Relay I25 is of the slow-to-release type and will thereforeremain operated during the complete impulsing period of the digit 5.

Magnet I60 follows the impulsing of relay I05 and in well-known mannersteps the wipers of the connector switch to the fifth bank contacts ofgroups 1 and 2. The operation of the connector switch'at this time isdependent upon whether line circuit 305 of station B is in use or isfree. Should line 355 of station B be in prior use, then ground will beencountered by control wiper I63 which causes busy relay I35 to operatefrom ground by way of wiper I63, armature I53 and working contact,contact I61 of oiT-normal spring set I35, armatures H4, I01, I23 andworking contact, winding of relay I35 to battery. Relay I35 locks toground by way of armature 129 and resting contact (as relay I25 restoresafter the impulsing of the digit 5 has been completed) armature I38 andworking contact and armature H3. At armature I35 and working contact,relay I35 connects busy tone to station A by way of condensers I34 andI5I, conductor IBI, conductor 55I, armature 52!, wiper 54I, bank contactand negative talking conductor of line 300 leading back to station A.

Assuming now that line 305 is free (idle), then there will be no groundon wiper I63. Relay I25 restores shortly after the impulsing period ofthe digit .5 and, at armature I29 and resting contact, extends ground towiper I63 by way of armature H3, I38 and resting contact, lower windingof relay I45, armature I29 and resting contact, armatures 101, N4,contacts I61 of off-normal spring set I65, and armature I53 and workingcontact. This ground is extended through wiper I63, bank contact,multiple C conductors to connector C bank contacts of group 1 and alsoto line 305, lower winding of line relay 306, winding of cut-01f relay3I6 to battery, causing relay I45 of theconnector switch and relay 3I6of line 355 to operate. The operation of cut-oflrelay 3I6 clears line305 of attachments. Although line relay 306 does not operate on callsincoming to line 305, the finder bank contacts of line relay 306 testbusy to a hunting finder switch because ground is normally connected toconductor 333 at armature 301 and resting contact.

Relay I45 of the connector switch locks to ground by way of armatureI09, armature I32, upper winding of relay I45 to battery. At armatureI46, relay I45 extends direct ground to wiper I63 for guarding theconnection from intrusion: at armature I39, removes dial tone from thecontacting circuit: at armature I48 connects grounded interruptedgenerator through upper winding of ringing cut-off relay I40, armatureI42 and resting contact, armature I48, armature I52 and working contact,Wiper I62, bank contact, multiple positive conductors to the positivethe first impulse of the digit of group 1, wipers 1', I12 and H3normally stand positioned just to the left of group 2, and extra-controlwiper I50 normally stands on the H, or home, contact just to the left ofthe first contact (H) of group 1. It will, therefore, be readily seenthat the two impulses of the dialled digit 2 are not required forpositioning wipers 11!, I12 and H3 with respect to group 2, but arerequired inthis instance for causing two energizations and twode-energizations of magnet I50 of odd-even relay I00, thereby to causearmatures I5l-I54 to select wipers IH-'I13 at the time that relay H5restores to normal and, at armature H9, prepares a point in the circuitof relay I25. It will also be observed that, at this point of operation,odd-even relay IE is in the restored position with magnet I59 drawing nocurrent. The connector switch is now in a position to respond to thedialling of the units digit of the telephone number of station E, andfrom this point on the operation is similar to that previously describedfor the case where the telephone number of station B was 15.

Assuming now that the telephone number of station E is 35 instead of 15or 25, then the dialling of the digit 3 causes the following operationof the connector switch Figure I. At armature I05 and resting contact,relay I05 transmits the first impulse of the digit 3 to relay I l 5 inseries with magnet I50, causing relay H5 to operate and magnet I50 toenergize. Armatures I55 and I56 operate responsive to the energizationof magnet I50 but perform no function at this time. Armatures EH- IM donot operate upon the energization of magnet I50. Relay H5 is of theslow-to-release type and, therefore, remains operated during thecomplete impulsing period of the digit 3. At armature H8, relay H5completes the series circuit through relay H5 and magnet I50 for theremaining two impulses of the digit 3 independent of armatures I24 andI21 and, at armature H5, opens a point in the circuit of relay I25 toprevent possible operation of relay I25 and magnet I60 at this time.

Relay I05 re-operates upon the cessation of 3 and, at armature I06,opens the series circuit through relay I I5 and magnet I50. Magnet I50correspondingly deenergizes thereby to cause the operation of armaturesI5I-I5t. Armature IM completes a circuit for relay I263 from ground,armature 55 i and working contact, armature 7% and working contact,armature III, armature I22 and resting contact, winding of relay I tobattery, causing relay I20 to operate and lock to ground by way ofarmatures I23, I26 and its.

At armature I05 and resting contact, relay I05 transmits the secondimpulse of the digit .3 to relay H5 in series with magnet I53 fromground, armature I06 and resting contact, armature H2 and workingcontact, armatures res, Iii, H3, windings of relay H5 and magnet I53 inseries to battery causing magnet I50 to re-energize and relay H5 toremain operated. Armatures I5I-- I54 remain operated during there-energization of magnet I50. Relay I05 re-operates upon the cessationof the second impulse of the digit 3 and, at armature I05, opens theseries circuit through relay H5 and magnet I50, magnet I50 de-energizingfor a second time thereby to cause armatures I5I-I54 to be restored. H

At armature I05 and resting contact, relay I65 transmits the thirdimpulse of the digit 3 to relay H5 in series with magnet I50 fromground, armature. I06 and resting contact, armature; I12

and working contact, armature I33, I31, H8, windings'of relay H5 andmagnet I50 in series to battery, causing magnet I50 to re-energize for asecond time and relay H5 to remain operated. As magnet I50 re-energizesand operates armature I56, a circuit is completed from ground, armatureI54 and resting contact, armatures I58, 'I2I, conductor I59, contact I-I(Figure 'I-A) of the extra-control bank, extra-control wiper I64,armature H6, interrupter armature I59, winding of magnet I60 to battery,thereby causing magnet I60 to self-drive the wipers of the connectorswitch to the first bank contact sets of groups 1 and 2. As extracontrolwiper I64 connects with the second contact (H) of its bank, the steppingcircuit for magnet IE9 is maintained by ground on contact H and, sincecontacts H-I8 are multipled together, magnet I60 continues to self-drivethe wipers of the connector switch until the wipers reach the respectivecontacts l9 and 29 of the banks.

. Relay I05 re-operates upon the cessation of the third impulse of thedigit 3 and, at armature IBS, opens the series circuit through relay H5and magnet I50. Magnet I50 correspondingly de-energizes for the thirdtime there by to cause a re-operation of armatures I5II54. Relay H5,however, is of the slow-torelease type and therefore maintains itsarmatures in the respective operating positions for a short interval. Asa consequence a circuit is completed from ground, armature I54 andworking contact, armature I08 and Working contact, armature III,armature I22 and working contact, conductor I68, contact I9 (Figure'I-A) of the extra-control bank, extra-control wiper I64 (the wipers oithe connector switch having reached contacts I9 and 29 of the banks inthe manner explained in the preceding paragraph), armature H6,interrupter armature I59, magnet to battery, thereby causing magnet I60to self-drive the connector switch wipers from contacts IS and 29 of thebanks to contacts [0 and 20. As extra-control wiper I64 connects withcontact I0 of its bank, there is no ground on this contact becausearmature I55 has restored and armature I54 has re-operated and,consequently, extra-control wiper I64 has completed its function ofcausing magnet I50 to self-drive the wipers of the connector switch tothe last bank contacts of groups 1 and 2. Relay H5 has completelyrestored and, at armature II9, prepared a point in the circuit of relayI25. It will be observed that, at this point of operation, odd-evenrelay I00 is in the re stored position with magnet I50 drawing nocurrent. The connector switch is now in a position to respond tothedialling of the units digit 5 of the telephone number of station B,and from this point on theoperat'ion is similar to that previouslydescribed for the case where the telephone number of station E was 15.

Should the first digit of the telephone number in the case justdescribed have been 4 instead of 3, then the same action occurs with thefollowing exceptions. The Wipers of the connector switch are standing oncontact 10 and 20 of groups 1 and 2 as described in the precedingparagraph for the digit 3, but in this instance relay H5 remainsoperated in the period: between the third and" fourth impulses of thedigit 4. At armatureI00 and restingv contact, relay I05transmits thefourth impulse of the digit 4? to relayi l l5in serie's'with magnet I50,causing magnet 150 to ire-energize for the third time and relay ll toremain operat ed. Armatures I5ll54 remain in the operated positionduring the third re-energization of magnet 150. Relay l05re-operatesupon the cessation of the fourth impulse of thedigit 4 and, at armatureI06, opens the series circuit through relay H5 and magnet I50. MagnetI55 correspondingly de-energizes for the fourth time thereby to cause.armatur es 151-154 to be restored. This restoration of armatures15|-l54 selects wipers 'IH TIZ and 113' at the time relay H5 restores tonormal and, at armature H9, prepares a point inthe circuit of relay I25.It will be observed that, at this point of operation, odd-even relay 100isin the restored position with magnet I50 drawing no current. Theconnector switch is now in a position to respond to the dialling of theunits digit of the telephone number of station B,

Should the first digit of the telephone number be 5 instead of 3 thenthe transmission of the third impulse of the dialled digit 5 causes thewipers of the conn'ectorswitch to be automatically rotated over the bankcontact sets of groups 1 and 2 to contacts and 2!! of groups 1 and 2 inthe manner previously explained for the case where the first digit was3. At the termination of the third impulse of the digit 5, armaturesl'54 are in the operated position and relay H5 also remains operated inthe period between the third and fourth impulses of the digit 5. Thewipers of the connector switch are now restingon the respective lastcontacts of groups 1 and 2. The fourth impulse of the digit 5 istransmitted from ground,

armature H16 and resting contact, armature H2 and workingcontact,,armatures 133, I31, H8, winding of relay H5 and magnet [56 inseries to battery, causing magnet 150 to again re-energize and relay H5to remain operated. Armatures T5|l54 also remain operated during thisre-energization of magnet I50. Relay Hi5 reoperates upon the cessationof the fourth impulse of the digit 5 and, at armature m6, opens theseries circuit through relay H5 and magnet [50. Magnet 15?}correspondingly de-energizes thereby to cause armatures T5l l'5 4 to berestored. Relay H5 remains operated in the period between the fourth andfifth impulses of the digit 5.

At armature Hi6 and resting contact, relay 7&5 transmits thefifthimpulse of the digit 5 to relay H5 in series with magnet T55,causing magnet 759 to again re-energiz e and relay H5 to remainoperated. As magnet 159 re-energizes and operates armature I56, a"circuit is completed from ground, armature I54 and resting contact,armature I56, 12L conductor 1.59, contact in (Figure 'I-A) of theextra-control bank, extra-control wiper F64, armature H6, interrupterarmature F59, winding of magnet 160 to battery, thereby causing magneti613 to self-drive the Wipers of the connector switch from the lastcontacts of groups 1 and 2 to the first contacts of groups 3 and 4. Asextra-control wiper L64 connects with the first contact (3!) of itsbank, the stepping circuit for magnet 1 5i) is maintained by ground oncontact 3| and, since contacts 3I-38 are multipled together, magnet I60continues to selfdrive the wipers of the connector switch until thewipersreach contacts 39 'and49 of the banks.

Relay I05 rte-operates upon the cessation of the digit 5 and, atarmature 106, opens the series circuit through'rela'y H5 and magnet15!]. Magnet 7'50 correspondinglyde-energizes thereby to cause are-operation of ar'matures'I-5l-l54. Relay H5 however, is of the slowto-release type and therefore, maintains its armatures in the respectiveoperated positions for a short interval. As a consequence a circuit iscompleted from ground, armature I54 and working contact, armature 188and Working contact, armature H1, armature I22 and working contact,conductor 15B, contact 39 (Figure 7-A) of the extra-control bank,extra-control wiper I54 (the wipers of the connector switch havingreached contacts 39 and 49 of the banks in the manner explained in thepreceding paragraph), armature H5, interrupter armature 1'59, winding ofmagnet let to battery, thereby causing magnet 155 to self-drive thewipers of the connector switch from contacts 39 and E9 of the banks tocontacts 38 and 48. As extra-control wiper Hi l connects with contact3i! of its bank, there is no ground on this contact because armature 55%has restored and armature E54 has re-cperated and, consequently,extracontrol wiper 76 3 has completed its function of causing magnet7653 to self-drive the wipers of the connector switch to the last bankcontacts of groups 3 and l. Relay H5 has completely restored and, atarmature H9, prepared a point in the circuit of relay 725. It will heobserved that, at this point of operation, odd-even relay is in therestored position with magnet 75!) drawing no current. The connectorswitch is now in a position to respond to the dialling of the unitsdigit of the telephone number of station B.

In a manner similar to that just described in the case where the firstdigit of the telephone number was 5, the wipers of the connector switchare positioned on the respective last contacts 5B and so of groups 5 and6 when the first dialled digit is 7. Also in a similar manner, thewipers of the connector switch are positioned on the respective bankcontacts It and 30 of groups 7 and 8 when the first dialled digit is 9.Since group 9 is the last of the odd numbered groups, it is unnecessaryto multiple contacts 91-98 of the extra-control bank together.

Should the first digit of the telephone number be 6 instead of 4 thenthe transmission of the third impulse of the dialled digit 6 causes thewipers of the connector switch to be automatically rotated over the bankcontact sets of groups 1 and 2 to' contacts to and 25 of groups 1 and 2in the manner previously explained in the case where the first digit was3. At the termination of the third impulse of the digit 6, armatures?5Il"54 are in the operated position. Relay l i 5 also remains operatedin the period between the third and fourth impulses of the digit 6. Thewipers of the connector switch are now resting on the respective lastcontacts of groups 1 and 2. At armatures Efilfi and resting contact,relay F05 transmits the fourth impulse of the digit 6 to relay H5 inseries with magnet 75!), causing magnet 159 to again reenergize andrelay H5 to remain operated. Armatures l5ll5 l remain in the operatedposition during this re-energization of magnet 755. Relay re-operatesupon the cessation of the fourth impulse of the digit 6 and, at armatureT06, opens the series circuit through relay '4 5'5 and magnet 75!).Magnet 15s correspondingly dcenergizes thereby to cause armatures EM-756to be restored. Relay H5 remains operated in the period between thefourth'and fifth impulses of the digit 6.

At armature I06 and resting contact, relay 105 --;.transmits thefifthimpulse; Of the digit '6 to relay I l 5 in series with magnet I50,causing magnet150 to again re-energize and relay H5 to remain operated.As magnet I50, re-energizes and operates armature I56, a circuit iscompleted from ground, armature I54 and resting contact, armatures I55,12!, conductor I59, contact I (Figure I-A) of the extra-control bank,extracontrol wiper I54, armature H5, interrupter armature I59, winding,of magnet I60 to battery, thereby causing magnet I60 to self-drive thewipers of the connector switch from the last contacts of groups 1 and 2to the first contacts of groups 3 and 4. As extra-control wiper I64connects with the'flrst contact (31') of its bank, the stepping circuitfor magnet I60 is maintained by ground on contact 3| and, since contacts31-38 aremultipled together, magnet I50 continues to self-drive thewipers of the connector switch until the wipers reach contacts 39 and 49of'the banks.

Relay I05re-op-erates upon the cessation of the .fifth impulse of thedigit 6 and, at armature .I06, opensthe series circuit through relay H5and magnet I50. de-energizes thereby to cause a re-operation ofarmatures I5l--I54. Relay H5 remains operated during the period betweenthe fifth and sixth impulses of the digit 6. At armature I06 and restingcontact, relay I05 transmits the sixth impulse of the digit 6 to relay 1l5 in series with magnet J50, causing magnet I50 to again re- Magnet I50correspondingly energize and relay H5 to remain operated. Ar-

matures I5 l-I54 remain in the operated position during thisre-energization of magnet I50. Relay I05 ,re-operates upon the cessationof the sixth impulse of the digit 6 and, at armature I06, opens theseries circuit through relay H5 and magnet I50. Magnet I50correspondingly'deenergizes thereby to cause armatures I5II54 to berestored. This restoration of armatures I5I--I54 selects wipers III, I12and 113 at the time relay H5 prepares a point in the circuit to relay Iat armature H9. It will be observed in a position to respond to thedialling of the unitsdigit of the telephone number of station In amanner similar to that just described. for

the .case where the first digit of the telephone number was 6, thewipers of the connector switch are positioned on the respective bankcontacts 50 and 60, of groups 5 and 6 when the first dialled digit is 8.Also in a similar manher, the wipers or the connector switch are posi-"tioned on the respective bank contacts I0 and 80 of groups 7 and 8 whenthe first dialled digit is 0. Since group 0 is the last of the evennumbered groups it is unnecessary to multiple the contacts 9 |98 of theextra-control bank together.

Assuming now that the calling station is station B; instead of stationA, then cut-off relay 3 l 6 (Fig. 3-B). would be hunted and seized bywiper 533. Battery through the windings of cut-off relay 3H; and linerelay 305, armature and working contact, conductor 333, bank contact,and wiper 533 would, therefore, shunt down relay 430,. causing relay430130 open the circuit of magnet 540 of the finder switch at armature43I, thereby stopping wipers 53L 532, and 533 on the bank contactsconnected to line 305. The restoration of relay 430 completes a circuitfor relay 440 from ground, armatures 424, 432, 454, winding of relay 440to battery, causing relay 440 to operate and lock to ground by way ofarmatures 454, 444 and 424. At armature 44!, relay 440 connects groundto conductor 413 of the finder switch by Way of ari'naturev 422 5 andworking contact, wiper 463 and bank contact, thereby to operate odd-tensrelay 5I0 and cut-ofi relay 3l6, the circuit for cut-off relay 3l5 beingcompleted through armatures 5I2, and 5| 4. At armature 439, relay 440shunts start relay 4| 0, causing relay M0 to restore and open thecircuit ofrelay 425 at armature 4 I 3. Relay 425 is of the slow-torelease type and, therefore, doesnot restore immediately but retainsrelay 44!) operated for a short interval at armature 424. At armature443, relay 440 opens another point in the circuit to relay 450, therebyto prevent the possible operation of relay 450 as, long as relay 440 isoperated. At armature M3 and resting contact, relay 4I0 completes acircuit to magnet 450 of the allotter before relay 425 has hadsufiicient time to restore. As relay 425 restores, this last circuit tomagnet 460 is opened at armature 428, and magnet 460 steps WipersMil-465 of the allotter to the bank contacts of the next line-finderswitch.

The operation of odd-tens relay 5l0 of the line-finder connects wipers53l, 532and 533 to conductors 55 I, 552 and 553 leading to conductorsI0], I02 and I03 of the connector switch (Figure 7) of the link by wayof armatures 5i I, 512v and 5l3 thereby to seize the connector switch,and

ground returned over conductors I03 and 553 from the connector switch isextended to wiper 533 and cut-off relay 306 before relay 425 in theallotter restores and opens the circuit of relay 440. The ground fromthe connector switch to wiper 533 is extended to the connector multiplebank contacts associated with conductor 333 thereby guarding telephonestation B from intrusion.

Cut-off relay 3l6, upon operating, disconnects the upper winding of linerelay 306 at armatures 3-B are typical for explanatory purposes, only,

and that this invention can be applied equally as well to any of themany well-known station line circuits;

Calls in a MOO-station system Assuming now that station A (Figure 3-A)desires to call station E (Figure 3-B) in a LOGO-station system, theneach link will comprise a line-finder switch, such as Figure 5, directlyconnected to a selector switch, such as Figure 6, and the selectorswitch (Figure 6) of the link will have access to connector switches,such as Fig. '7. The connector switches are divided into groups foraccessing the lines of the telephone stations in the manner outlined inthe previous short description of Figure 8.

Assuming further that a linkcomprising linefinder Figure 5 and selectorswitch Figure 6 is available at the moment and will be assigned to thecall by allotter Figure 4 responsive to station A initiating a call,

then in the manner described in the section titled Calls in a 100-Station System, line-finder Figure hunts for and seizes line 300 ofcalling station A. a

' consequence, even-tens relay 520 of the finderswitch and cut-off relay320 of the line 359 are operated, also in the manner described in the523, thereby to seize the selector switch. Ground returned overconductors 563 and 553 from the selector switch is extended to wiper 545and out-- 01f relay 320 before relay 525 in the allotter restores andopens the circuit of relay The ground from the selector switch to wiper543 is extended to the connector multiple bank contacts associated withconductor 345. thereby guarding telephone station A from intrusion.

Cut-off relay 325, upon operating, disconnects the upper winding of linerelay 3 it at armatures 32! and 322 to free the line from attachments,butline relay 3H3 remains operated through its lower winding and thewinding of cut-off relay 320. At armature 323, cut-ofif relay 324iremoves the last ground from start relay iiil of the finder-switchallotter (relay 450 having restored in the meantime), thereby freeingthe allotter from control by station A. The finder-switch allotter isnow free to assign a finder switch to the next calling line.

Line 300 of station A is connected to line relay 605 of the linkselector switch by way of conductors 55!, 60!, 552 and 652, therebycausing relay 605 to operate. At armature E555 and work ing contact,relay 655 completes the circuit to relay 6H], causing relay 610 tooperate. At armature Bl l, relay 6M returns ground to conductor 603 andconductor 553 of the link finder switch. Dial tone is supplied tostation A by way of armature 536 and resting contact, condenser 634,armature 658 and resting contact, conductor 602, conductor 552, armature522, wiper 5 52, bank contact, and positive talking conductor of line300 leading back to station A.

Upon hearing the well-known dial tone. the calling person at station Adials the number of station B.which, in this instance, will be assumedto be 215. Responsive to the dialing of digit 2, the circuit to linerelay 555 is interrupted two times, relay 555 restoring momentarily foreach impulse and, at armature 655, opening the circuit to relay 5H].Relay 555, however, is of the slow-to-release type and, therefore, doesnot restore during the impulsing period. Consequently. the circuitscontrolled by relay 605 are not disturbed.

At armature 606 and resting contact, relay 605 transmits the firstimpulse of the digit 2 to relay 615 in series with magnet 558 of oddevenrelay 603, causing relay M5 to operate and magnet 65!! to energize. Thisseries circuit may be traced from ground by way of armature armature 605and resting contact, armature hi2 and working contact. armature 52 i,winding of relay 6I5, winding of magnet 55%! to battery. Armatures 655and 556 of odd-even relay 5% are operated responsive, to theenergization of magnet 650 but perform no functions at this time.Armatures 65!-654 of odd-even relay 6% do not operate u on theenergization of magnet Relay 615 is of the slow-to-release type andwill,

20 therefore, remain operated during the complete impulsing period ofthe digit 2.

Relay 555 re-operates upon the cessation of the first impulse of thedigit 2 and, at armature 5%, opens the series circuit through relay CH5and magnet 555. Magnet 555 correspondingly de-energizes thereby to causethe operation of armatures I-554. Armature i554 completes a circuit forrelay 625 from ground, armature i and Working contact, armature 558 andworking contact, armature E22 and resting contact, Winding of relay 625to battery, causing relay 521! to operate and lock to ground by way ofarmatures 523 and 559. Relay EH5 remaining operated in the periodbetween the first and second impulses oi the digit 2 retains the testingcircuit of oddtens control wiper 653 open at armature 5E9, therebymaking it impossible for wiper 6553 to hunt for a free connector switchin group "1 at this time.

At armature 655 and resting contact, relay 6G5 transmits the secondimpulse of the digit 2 to relay 6 i 5 in series with magnet 655 fromground, armature 633, armature 6GB and resting contact, armature M2 andworking contact, armature M8, windings of relay M5 and magnet 555 inseries to battery, causing magnet 550 to re-energize and relay 6 l 5 toremain operated. Armatures 65l'-654 remain operated during there-energization of magnet 6%.

Relay 555 re-operates upon the cessation of the second impulse of thedigit 2 and, at armature 5%, opens the series circuit through relay 5E5and magnet 655, magnet 65!] cle-energizing for a second time thereby tocause armatures 65i854 to be restored. Relay 6i5 restores after a shortinterval. The restoration of relay EH5 connects the windings of relay645 and magnet 565 in series from ground to battery, with wiper 5'53tapped in between the two windings. These circuits may be traced fromwiper 6'13, armature 553 and resting contact, armature 655 and restingcontact, winding of relay 645, armatures B93, 626, 631 and restingcontact, and 609 to ground, and from wiper 613, armature 553 and restingcontact, armature 645 and resting contact, armatures 615, 525, 538,interrupter armature 659, winding of magnet 665 to battery. Magnet 65Bcannot operate through the high resistance of relay 645, but relay 645can operate through the low resistance of magnet 66!) except when relay645 is shunted by ground on .wiper 613 which will be the case if wiper6'33 connects with a busy bank contact.

As previously explained, the groups and 2 of the selector switch banksare in alignment with each other, i. e., the first contact set of group1 is in alignment with the first contact set of roup 2, etc. Odd-tenswipers 56L 662 and 553 normally stand on the respective first contactsof group 1, and wipers 5H, B72 and 613 on the respective first contactsof group 2. It will, therefore, be readily seen that the two impulses ofthe dialled digit 2 are not required to operate magnet 555 for thepurpose of advancing wipers 575, 512 and 613 to group 2, as these wipersare already standing on the first bank contact set of group 2. The twoimpulses of the digit "2 are required, in this instance, for causing theenergization and de-energization of magnet 55B of odd-even relay 500 twotimes, thereby to cause armatures 55i-553 to select even-tens wipers 6',612 and M3 at the time relay EH5 restores to normal and, at armature 521control wiper .6113. Consequently, BJ3-wiil now automatically hunt for,a free connector switch connected "to a bankscontactset of .group 2. Itwill :be observed that, at this point of operation, odd-even "relay 600is. in the restored position with magnet fifitwdrawing no .current.

Should the first :bank contact set .of 1groupf2" he in prior use'(busy') when the testing circuit to wiper .613 is completed, then therewould be ground on wiper 613. As :a consequence, when magnet 650de-energizes :at the conclusion of :the second impulse of the digit 2,the ground would be extended to armature 646 and, hence, would shuntrelay 645 thereby to cause magnet 666 to self-drive the wipers of theselector switch inwell-known manner to search for :a free connectorswitch in group 2-. When wiper 613 contacts a free connector switch, theautomatic hunting will cease and relay 645 will operate to extend line360 through to the selected connector switch in a manner to be describedin a later paragraph.

Should all of the connector switches of group 2 be in prior use whentested by wiper 613,

then all-trunks-busy relay B35 is operated fromswitch wipers to thefirst bank contact set (3!) of group 3': at armature 63'! and workingcontact,

completes :an obvious lockin circuit for itself;

and, at armature 636 and working contact, connects busy tone tocondenser 634 thereby to in- ,form the callin person at station A thatall of the connector switches having access to station B are in prioruse.

Assuming now that the connector switch connected to the first contactset of group 2 is free Widle), and that this connector switch isillustrated in Figure 7, then there will be no ground on the first-'loank contact set of group ".2." Relay 645, therefore, operates inseries with magnot 660. .At armature 5'46, relay 645 disconnects magnet659 from wiper 673 to prevent stepping r of the wipers: atarmature632.,1ocks itselfirom ground, armatures .6! I, '632, Winding of .relay64'5,

armatures 619, 6,25,. 638,, interrupter armature 6.59, winding of magnet659.110 battery: at armature .645 and working contact, connects ground.to wiper .613 .by way of .armatures ii I 'l, 632, armature E45 andworking contact, armature 6.53 and resting contact to guard connectorFigure '7 from intrusion: .at armatures .641 and 618, disconnects relay6.05 from conductors 5M and 592.; and, at armatures .641 and .648 andassociated worln'ng contacts, extends line 300 to connector 7 switchFigure '7 by way of wipers 6-H and .612.

Relay 6]!) is restored to normal as a resultof the operation of relay64.5,and the release of relay 60.5, but relay BID is slow to .restore. nnew locking circuit is, therefore, completed 'for relay 629 from groundreturned over conductor 103 from connector switch Figure '7, bank .con-

tact, wiper 613, armature 55.3 and resting contact, armature fi lfixandworking contact, armatures H3, 625, $3] and resting contact, 623,winding of relay 620 to battery, thereby preventing relay 620 fromrestoring when its original locking ground is disconnected at armature689.

1a of :relay .6211 remaining locked .aiter relay 6|!) has restored,:relay .645 is maintained inthe locked position from the ground :onwiper 613:, armature 2653 and resting contact, :armature 1646:andworking contact, winding of relay .645, :armatures 1619, 625, 6 38,interrupter armature 659, winding of magnet 6.6.0 to battery. "Theground .on wiper 61,3 also extended through .armature 632 to conductor.603 for retaining line relay 34a and -.cut-:off:relay i320 of line 390in the operated position. From this point on, connector :switch Figure'7 is operated by impulses :from station A to connect with, and signal,station "23 in the :manner described 'in the sec-- tion titled "Calls ina -:Station System.

When :the conversation between stations A and .B has .been terminatedand :both telephone handsets "returned to the respective cradlesytheconnectionis released. The .line circuits 1300 and 3305,, the :finderswitch Figure .5, and the con- :nector :switch Figure "7 are :rel-easedin the :man- :ner "described in the section titled Calls :in" alilo-Station System. The selector .switch :Figure is released andrestored to normal in the following "manner. The release of connectorswitch Figure '7 removes ground f-rom'wiper 613 thereby openingthelocking circuits of relays fitllzand e645, causing these two relaysto restore. All of the relays of the selector switch are new at normal,and a homing circuit for the selector switch .is completed from ground,armature 633, armature 606 and resting contact, armature-M2 and. restingcontact, pit-normal springs BT65, armature 638, interrupter armature6-59, winding of magnet .6160 to battery. Magnet :660, consequently,self-drives wipers 6'6l--613 in wellmanner until the wipers arrive attherespective :first bank contact sets of groups I and "i2," whereupon thecircuit of magnet 66.0 is opened at :off-rnorma-l springs 665.

Assuming now that the telephone number of station "B""-is instead of2'15, then "the dialling of the first :digit "1 causes the follow- :ingoperation of selector switch Figure 6. The circuit to line relay 605 :isinterrupted once and relay 605, at armature 306., opens the circuit torelay :6), but relay '6! is of the slow-to-release type. .At armature606 and resting contact, relay 1605 transmits the impulse to relay -6l5in series with magnet 650, causing relay 615 to op- -erate and magnet550 to energize. Armatures 55 and 6516 operate responsive to theenergiza- -tion of magnet :850 but perform no functions at this time.Armatures 651- 554 do not operate upon the energization of magnet 650.

'Relay 605 re-operates upon the cessation of the impulse of the digit "1and, at armature 506, opens the series circuit through relay -6 I15 andmagnet 65B. Magnet 65!) correspondingly tie-energizes thereby to causethe operation of armatures 651-654. Armature 654 completes a circuit forrelay 6-2-0 from ground, armature 654 and working contact, armature 608and working contact, armature 622 and resting contact, winding of relay620 to battery, causing relay 620 to operate and "lock to ground by wayof armatures 623 and 6%. Relay M5 restores after a short interval. Therestoration of relay M5 connects the windings of relay 5'45 and magnet660 in series from ground to battery, with wiper fist-tapped in betweenthe two windings. Mag net 66!) cannot operate'through the highresistance of relay 645, but relay 845 can operate through :the lowresistance of magnet B60 ex-- ceptwhen relay 645 is shunted by ground on'wiper' 663 which will be the case if wiper 663 connects with a busybank contact.

As previously explained, wipers (Nil, 662 and 663 normally stand on therespective first bank contacts of group 1. It will, therefore, bereadily seen'that the one impulse of the dialled digit 1 is not requiredto operate magnet 660 for the purpose of advancing wipers 66!, 662 and663 to group 1, as these wipers are already standing on the first bankcontact set of group "1. The one impulse of the digit 1 is required, inthis instance, for causing one energization and one de-energization ofmagnet 656 of odd-even relay 60B, thereby to select odd-tens wipers 66!,662 and 663 at the time relay 615 restores and, at armature 6l9,establishes the testing circuit for odd-tens control wiper 663.Consequently, wiper 663 will now automatically hunt for and find a freeconnector switch connected to a bank contact set of group 1 in a mannersimilar to that previously described for wiper 613. From this point on,connector switch Figure '7 connects with, and signals, station B in amanner similar to that described in the section titled Calls in aIOO-Station System.

The release of selector switch Figure 6 upon the termination of theconnection just described, is the same as that previously explained forthe case where the telephone number of station E was 215, with theadditional condition that odd-even relay 600 must be again energized andde-energized in order to return armatures 85l-654 to their normalpositions. This additional operation cycle of odd-even relay 600 isaccomplished in the following manner: the restoration of relay 645completesa circuit to magnet 650 of odd-even relay 600 from ground,armature 654 and working contact, armature 608 and resting contact,armature 649, interrupter armature 655, winding of magnet 650 tobattery, causing magnet 650 to energize. At armature 655, magnet 650opens its energizing circuit thereby to cause armatures 65|--654 torestore to normal, whereupon the energizing circuit of magnet 650 ismaintained open at the working contact of armature 554.

Assuming now that the telephone number of station E is 315 instead of215 or 115,

'then the dialling of digit 3 causes the following operation of selectorswitch Figure 6. The circuit to line relay 605 is interrupted threetimes, relay 605 restoring momentarily for each impulse. At armature 606and resting contact, relay 605 transmits the first impulse of the digit3 to relay 6l5 in series with magnet 650, causing relay M5 to operateand magnet 650 to energize. Armatures 655 and 656 operate responsive tothe energization of magnet 656 but perform no functions at this time.Armatures 651-654 do not operate upon the energization of magnet 656.

Relay 6l5 due to its slow-to-release characteristic will remain operatedduring-the complete impulsing period of the digit 3. I

Relay 605 re-operates upon the cessation of the first impulse of thedigit 3 and, at armature 606, opens thev series circuit through relay M5and magnet 650. Magnet 650 correspondingly de-energizes thereby to causethe operation of armatures 65l-654. Armature 654 completesa circuit forrelay 620 from ground, armature 654 and working contact, armature 668and working contact, armature 622 and resting contact, winding of relay626 to battery, causing relay 62!) to operate and lock to ground by wayof armatures 623 and 609. Relay 6|5 remains operated in the periodbetween the first and second impulses of the digit 3, and retains thetesting circuit of odd-tens control wiper 663 open at armature 6L9.

At armature 666 and resting contact, relay 665 transmits the secondimpulse of the digit 3 to relay M5 in series with magnet 650 fromground, armature 633, armature 666 and resting contact, armature (H2 andworking contact, armature 618, windings of relay 6 i 5 and magnet 656 inseries to battery, causing magnet 650 to re-energize and relay M5 toremain operated. Armatures Bid-654 remain operated during there-energization of magnet 656. Relay 665 re-operates upon the cessationof the second impulse of the digit 3 and, at armature 666, opens theseries circuit through relay 6 I 5 and magnet 656, magnet 656de-energizing for a second time thereby to cause armatures |654 to berestored. Relay 6l5 remains operated in the period between the secondand third impulses or" the digit 3, and retains the testing circuit ofeven-tens control wiper 6'53 open at armature 6H6.

At armature 606 and resting contact, relay 605 transmits the thirdimpulse of the digit 3 to relay 6P5 in series with magnet 656 fromground, armature 633, armature 666 and resting contact, armature 6l2 andworking contact, armature 1H8, windings of relay 615 and magnet 550 inseries to battery, causing magnet 656 to re-energize for a second timeand relay M5 to remain operated. As magnet 656 re-energizes and operatesarmature 656, a circuit is completed from ground, armature 656 andresting contact, armatures 656, 6H, 62%, conductor 629, contact ll(Figure 6-A) of the extra-control bank, extracontrol wiper 664, armature636, interrupter armature 659, winding of magnet 666 to battery, therebycausing magnet 666 to self-drive the wipers of the selector switch fromthe first bank contact sets of groups 1 and 2. As extracontrol wiper 664connects with its second bank contact ([2), the stepping circuit formagnet 666 is maintained by ground through armature 6I6 and, sincecontacts I2l9 inclusive of the extra-control bank are multipledtogether, magnet 666 continues to self-drive the wipers of the selectorswitch until the wipers reach contacts [6 and 26 of the banks.

Relay 665 re-operates upon the cessation of the third impulse of thedigit 3 and, at armature .606, opens the series circuit through relay6H5 and magnet 650. Magnet 65!] correspondingly ole-energizes for athird time thereby to cause the re-operation of armatures 65I-654. Relay6i5, however, is of the slow-to-release type and, therefore, maintainsits armatures in the respective operated positions for a short interval.As a consequence, a circuit is completed from ground, armature 654 andworking contact, armatures 668, 622, GM and associated working contacts,conductor 628, contact I0 (Figure G-A) of the extra-control bank,extra-control wiper 665 (the wipers of the selector switch havingreached contacts I0 and 2B of the banks in the manner explained in thepreceding paragraph), armature 638, interrupter armature 666, winding ofmagnet 666 to battery, thereby causing magnet 666 to self-drive theselector switch wipers from contacts I6 and 26 of the banks to contacts31 and 4| of groups 3 and .4. As extra-control wiper 666 connects withcontact 3! of its associated bank. there is no ground on this contactbecause armature 656 has restored and armature 656 has re-operated and,consequently, extra-control wiper 66s hascompleted its functionofcausing magnet- 6 66 to self-drive thewipersof the selector switch tothe first bank contacts of groups 3 and 4. At this point, relay 6.!5 hascompletely restored and, at armature 6l9, completed the testing circuitfor wiper 663 so that wiper 663 will now automatically hunt for a freeconnector switch connected to a bank contact set of group 3. From thispoint on, the operation of the selector switch is similar to thatdescribed for the selector switch when the first digit of the telephonenumber of station B was 1.

Should the first digit of the telephone number in the case" justdescribed have been 4 instead of 3, then thesame action occurs withthef-ollowing exceptions. The wipers of' the selector switch are.standing on contacts 3! and, 4! of group 3 and 4 as described. in thepreceding paragraph for the digit 3, but in this instance relay 6|5remains operated in'the period between thethird and fourth impulses ofthe digit 4, and retains the testing circuit of odd-tens control wiper663 open at armatur 6l9'. At armature- 866' and resting contact, relay665' transmits the" fourth impulse of the digit 4' to relay M5 in serieswith magnet 656, causing magnet 666 to reenergi'ze for the third time.and relay 6!?) to remain operated. Armatures 65l654' remain inthe'op'erated position during the third re-energization of magnet 656;Relay 665 re-operates upon the. cessation of' the fourth impulse of thedigit 4 and, atarmature 666, opens the series circuitthrough relays 615and magnet 656. Magnet 656 correspondingly de-energizes for the fourthtime thereby to: cause armatures 66 i--65'6 to. be restored. Thisrestoration of armatures 65i-654 selects. wipers 671, 612 andv 613 atthe time relay Hi5v restores to normal and, at armature 619, establishesthe testing circuit'for eventens control wiper 613. Consequently, wiper616 will now automatically hunt for a, free connector switch connectedto a bank contact set of group [4]?! Should the first digit. ofthetelephone. number be-5. instead of 3,, then the transmission of thethird impulse of. the dialled. digit. 5 causes,

the wipers ofthe selector switch to be. automatically rotated over thebank contact set of groups "l'and 2 in the manner previously explained,in the. case where. the first digit. was 3,. At the terminationof thethird'imp-ulse off the digit. 5,

armatures 65l6.54' are in the op'era'tedposition, and relay 615 also.remain operated; The wipers. of. the selector switch are now resting onthe respective first contacts of groups 3 and 4'. Relay 6I5' remainsoperated inv the period between the third, and fourth impulses of thedigit 5', and retains the testing circuit of odd-tens control wiper663open at armature 619. The fourth impulse of'the digit 5 istransmitted from ground; armature'633', armature 666 and restingcontact, armature 612 and working contact, armature 6 l 8; windings ofrelay 6 i5" and magnet 656 in series to battery, causing magnet 656. toagain re-energize and relay 615 to remain operated. Armatures 65l--654also remain operated during this reenergization of magnet 650. Relay 606re-oper ates upon the cessation of the fourth impulse of' thedigit 5and, at armature 666; opens the series circuit through relay M5andmagnet 650. Magnet 650- correspondingl-y de-energizes therebyto causearmatures-65l654 to be restored. Re-' lay 6i5-- remains operated in theperiod between the fourth and fifth impulses of the digit"5',and retainsthe testing circuit of even-tens control wiper 613 open alt-armature-619". At armature 6'66 and resting contact, relay 665 transmits thefifth impulse, of the digit 5 to relay 6|;5 in series with magnet 65!),causing magnet 656 to again re-energize; and relay 6!! to remainoperated. As magnetv 656 re-energizes and operates armature 6.56,. acircuit is completed from ground, armature 654 and resting contact,armatures 656, 6H, 62], conductor 62 9', contact 3! (Figurefi-A) of theextra-control bank, extra-control wiper 664, armature 638:, interrupterarmature 659, winding of magnet 666 to battery, thereby causing magnet666 to self-drive the. wipers of the selector switch from the first bankcontact sets of groups 3 and 4.- As extra-control wiper 664 connectswith the second contact of (32) of its bank, the stepping. circuit formagnet 666 is maintained by ground through armature 6 I 6 and, sincecontacts 31-3 9 inclusive of the extra-control bank aremultipledtogether, magnet 666 continues to self.- drive' the wipers of theselector switch until the wipers reach contacts 36v and so of the banks.

Relay 665 re-operates upon the cessation of the fifth impulse of thedigit .5 and, at armature 666, opens the series circuit through relay6l5, and magnet. 656. Magnet 656 correspondingly de-energizes. therebyto cause the re-operation ofarmatures: Bill-654. Relay 616', however, isof.-

the slow-to-release type and, therefore, maintains its armatures in therespective operated positionsfor a short interval. As a consequence, acircuit is completed from ground, armature 654 and. working contact,armatures 668, 622,6 l4 and associated working contacts, conductor 628,contact 36 (Figure 6-A) of the extra-control bank, extra-control wiper664 (the wipers of the selector" switch having reached contacts 36 and4,0 of the banksin the manner explained in the preceding aragraph),armature 6,38, interrupter armature, 659, winding of magnet 666 tobattery, thereby causing magnet 660 toself-drive the wipers of theselector switch from contacts 36 and 40 of the banks to contacts 5| and6! of groups 5 and" 6. As extra-control wiper 664, connects with contact5| of its bank, there is no ground on thisv contact because armature 656has restored and armature 654 has re-operated and, consequently,extra-control Wiper 664 has completed its func I tion of causing magnetv666 to self -drive the wipers of the selector switch to the first bankcontacts of groups 5 and 6. At this point, relay 616 has completelyrestored and, at armature 619, completedv the testing circuit for wiper663 sov that wiper 663 will now automatically hunt for a free connectorswitch connected to a bank contact set of group 5. From this point on,the operation of the selector switch is similar to that de-'-= scribedfor the selector switch when the first digitof the telephone of stationE was 1.

In a manner similar to that just described for the case where the firstdigit of the telephonenumber was 5, the selector switch is caused tohunt for a free connector switch connected to a. bank contact set ofgroup 7 when the first dialled digit is 7',- 7 Also in a similar manner,the selector switch is caused to hunt for a free connector switchconnected to a bank contact set of group 9 when the first dialled digitis 93* Since group-9isthelast of the odd-numbered groups. it isunnecessary to multiple the contacts; 9l-99f of the extra-control bank.together or to connect ground: to contact 9L Should the first-digit ofthe telephone number be 6" instead of. 4, then. the. transmission. ofthethird impulse ofv the. dialleddigit 6 causes thawipers of the selectorswitch to beautomati-v cally rotated over the bank contact sets ofgroups "1 and 2 in the manner previously explained for the case wherethe first digit was 3. At the termination of the third impulse of thedigit 6, armatures 65l-filll are in the operated position, and relay t lalso remains operated. The wipers of the selector switch are now restingon the respective first contacts of groups 3 and 4. Relay tit remainsoperated between the third and fourth impulse of the digit 6, andretains the testing circuit of odd-tens control wiper 653 open atarmature M9. At armature tilt and resting contact, relay 6&5 transmitsthe fourth impulse of the digit 6 to relay M5 in series with magnet est,causing magnet tilt to again re-energize and relay M5 to remainoperated. Armatures 55l-ii5i4 remain in the operated position duringthis re-energization of magnet 650. Relay 605 re-operates upon thecessation of the fourth impulse of the digit 6 and, at armature 6%,opens the series circuit through relay 615 and magnet 65%. Magnet 6%correspondingly de-energizes thereby to cause armatures 65lii54 to berestored. Relay ii i 5 remains operated in the period between the icurthand fifth impulses of the digit '6, and retains the testing circuit ofeven-tens control wiper 6E3 open at armature 619.

At armature tilt and resting contact, relay 6H5 transmits the fifthimpulse of the digit 6 to relay 615 in series with magnet E56, causingmagnet 650 to again re-energize and relay EH5 to remain operated. Asmagnet $56 re-energizes and operates armature 656, a circuit iscompleted from ground, armature 654 and resting contact, armatures $56,Ell, 62 I, conductor $29, contact 31 (Figure 6-A) of the extra-controlbank, extra-control Wiper $54, armature 633, interrupter armature 658,winding of magnet 660 to battery, thereby causing magnet 660 toself-drive the wipers of the selector switch from the first bank contactsets of groups 3 and 4. As extra-control Wiper $64 connects with thesecond bank contact (32) of its bank, the stepping circuit for magnetElli) is maintained by ground through armature BIG and, since contacts323e inclusive of the extra-control bank are multipled together, magnet66% continues to self-drive the wipers of the selector switch until thewipers reach contacts 313 and ll! of the banks.

Relay 6&5 re-operates upon the cessation of the fifth impulse of thedigit 6 and, at armature Gilli, opens the series circuit through relayBIB and magnet Magnet 650 correspondingly de-energizes thereby to causethe re-operation of armatures dbl-K55 i. Relay (H5 remains operated intheperiod between the fifth and sixth impulses of the digit 6, andretains the testing circuit of odd-tens control wiper 663 open atarmature 6 I 9. At armature tilt and resting contact, relay (585transmits the sixth impulse of the digit 6 to relay ii i 5 in serieswith magnet B50, causing magnet 650 to again re-energize and relay M5 toremain operated. Armatures 651-4554 remain in the operated positionduring this re-energization of magnet tee. Relay 6335 re-operates uponthe cessation of the sixth impulse of the digit 6 and, at armature 5%,opens the series circuit through relay M5 and magnet B. Magnet 650correspondingly ole-energizes thereby to cause armatures 65lt54 to berestored. This restoration of armatures 65 l-i5 i selects wipers 67 I,612 and El 3 at the time relay 615 establishes the testing circuit foreven-tens control wiper '6l3. Consequently, wiper 613 will nowautomatically hunt for a free connector switch connected to a bankcontact set of group 6.

In a manner similar to that described for the case where the first digitof the telephone number was 6, the selector switch is caused to hunt rora free connector switch connected to a bank contact set of group 8 whenthe first dialled digit is 8. Also in a similar manner, the selectorswitch is caused to hunt for a free connector switch connected to a bankcontact set of group 10 when the first dialled digit is 0. Since group 0is the last of the even-numbered groups, it is unnecessary to multiplethe contacts 9l99 of the extra-control bank together or to connectground to contact 9i.

Stepping circuits of selector Figure 6 In order that the variousstepping circuits of selector Figure 6 may be more readily apparent,Figure 9 has been developed to show these stepping circuits in simplediagram form. Only a sufficient number of relays and contacts areincluded in Figure 9 to enable the tracing of the stepping circuits,certain of the intermediate relay contacts being indicated by the symbolX.

Referring now to Figure 9, control wiper 663 and its related bank forgroup 1, and control wiper 8'53 and its related bank for group 2 areshown. The control banks for all other odd and even groups areomitted,.as well as the negative and positive conductor wipers andrelated banks. extra-control wiper 664 and its associated bank contactsfor groups 1 and 3 are also shown, it being understood that there are noextra-control bank contacts for group 2.

The descriptions of the stepping circuits of selector Figure 6 detailedin the section titled Calls in a 1000-Station System may be readilyapplied to Figure 9 when the dialed selector digit is 1, 2,7, (377 ii4il'laving described the invention, What is considered new and is desiredto have protected by Letters Patent is set forth in the followingclaims:

1. In a telephone system, a calling line, a group of trunks, sets ofbank contacts connected to said trunks, means for extending said line toone of said trunks, means for, busy-marking the set of bank contactsconnected to said one trunk, means whereby said second-mentioned meansis operated in response to said extension, a second calling line havinga dial, a switch including a relay, conductors and wipers, said wipersstanding on said one set of bank contacts connected to said onetrunk,means for extending said second line to said switch, means for operatingand restormg said relay, means whereby said fifth-mentioned means iscontrolled by an impulse from said dial received over said secondcalling line, means for connecting said wipers to said conductors ofsaid switch thereby to connect said conductors to said one set of bankcontacts, means whereby said seventh-mentioned means is operatedresponsive to said operation and restoration of the relay, means forcausing said wipers to move from said one set of bank contacts to theset of bank contacts connected to another of said trunks, means wherebysaid ninth-mentioned means is operated responsive to the busy-marking ofsaid one set of bank contacts, means for connecting said second linethrough said conductors and said wipers to said other trunk, means fordisabling said connection of said second line with said other trunk,means for again operating and restoring said relay, means whereby saidlast-mentioned means is sesame connecting said wipers from saidconductors thereby to free said conductors from said set of bankcontacts connected to said other trunk, and means whereby saidlast-mentioned means is operated responsive to said last-mentionedoperation and restoration of said relay.

' 2. The telephone system claimed in claim 1 together with means forreturning said Wipers from said set of bank contacts connected to saidother trunk to said one set of bank contacts connected to said onetrunk.

3. In a telephone system, an automatic switch having a self-interruptedwiper-driving magnet, an operating circuit for said magnet, a set ofwipers, rows of bank contacts accessible to said wipers, said wipersstanding on one of said rows of bank contacts, and a relay, means foroperating and restoring said relay, means whereby said first-mentionedmeans is controlled by the first impulse of a received series of threeimpulses, means for partly preparing the operating circuit for saidwiper-driving magnet, means whereby said third-mentioned means isoperated responsive to the operation and restoration of said relay,means whereby said first-mentioned means is controlled by the secondimpulse of said series of impulses for operating and restoring saidrelay a second time, means for further preparing said operating circuitfor said magnet, means whereby said sixth-mentioned means is operatedresponsive to the second operation and restoration of said relay, meanswhereby said first-mentioned means is controlled by the third impulse ofsaid series of impulses for operating and restoring said relay a thirdtime, means for completing said operating circuit for said magnet tocause said magnet to automaticallyself-drive said wipers across said onerow of bank contacts to the next succeeding row of bank contacts, meanswhereby 5. For use in a telephone system, an automatic switch havingincoming conductors over which impulses are received and two sets ofwipers, a wiper switching relay, means for energizing and de-energizingsaid switching relay, means Whereby said "first-mentioned means iscontrolled by each impulse received over said incoming conductors,contacts on said relay, means whereby said contacts are operated in onemanner in response to a first de-energization of said relay after itsfirst energization, and operated in another manner responsive to asecond de-energization of said switching relay after a secondenergization, said contacts switching through a connection to one set ofwipers when operated in said one manner and switchingthrough aconnection to the other set of wipers when operated in said othermanner. i

6. In a telephone system, a calling line having a dial, a switch havinga relay, circuit means, and two sets of wipers, one of said sets ofwipers normally connected to said circuit means through said relay, saidother set of wipers normally disconnected from said circuit means atsaid relay, means for extending said calling line to said switch, meansfor causing two difierent operations of said relay, said two differentoperations consisting of an operation of said relay followed by arestoration or said relay, means whereby said last-mentioned means iscontrolled by a digit dialed over said calling line, contacts on saidrelay, means whereby said contacts are operated responsive to said twodifferent operations of said relay for disconnecting said one set ofwipers from said circuit means and for connecting'said other set ofwipers to'said circuit. means, means for connecting said calling linethrough saidcir cuit means to said other set of wipers, means fordisconnecting said calling line from said other set of wipers, means forcausing a recurrence of said two different operations of said relay,means whereby said last-mentioned means is controlled by saiddisconnection, and means whereby said contacts are restored responsiveto said last two different operations of said relay for disconnectingsaid other set of wipers from said circuit means and for reconnectingsaid one set of wipers to said circuit means.

7. In a single-motion numerical switch having incoming conductors overwhich impulses are received and two sets of wipers, each set with aplurality of groups of bank contacts accessible thereto, saidpluralities of groups arranged such that as one of said sets of wipersmoves over contacts in the groups of one plurality of groups, the otherset of wipers moves across corresponding contacts in correspondinggroups'in the other plurality of groups, said one set of wipers normallyresting upon the first bank contact of the first of said groupsaccessible thereto, said other set of wipers normally restlng'upon thefirst bank contact of the first of said groups accessible thereto, meansfor stepping said wipers'to the next succeeding pair of correspondinggroups of bank contacts, means whereby said first mentioned means iscontrolled by the third impulse in a series of received impulses and byeach oddnumbered impulse in said series thereafter received, and meansfor preventing the wipers from stepping to succeeding groups in responseto even-numbered pulses.

8. In a numeric-a1 switch having first and second sets ofwipers,odd-numbered groups of outlets and even-numbered groups ofoutlets acces sible respectively to said first and second sets ofwipers, incoming conductors connected to said switch and over whichimpulses are received, a wiper switching relay; means for-energizing andde-energizing said switching relay; means whereby said first-mentionedmeans is controlled by each one of a series of impulses received oversaid conductors, contacts on said relay; means whereby said contacts areoperated in response to each odd-numbered energization andde-energization and are restored in response to each even numberedenergization and de-energization, said contacts switching through aconnection to said first set of wipers when operated, and switchingthrough a connection to said second set of wipers when restored; meansfor stepping simultaneously each of said sets of wipers to the nextsucceeding pair of groups of, outlets accessible to said set of wipers;means: whereby said lastmentioned means is controlled by the thirdimpulse in said series of impulses and thereafter by each succeedingodd-numbered impulse in the series; one of said groups of outletspre-determined by the number of impulses in the series of impulsesreceived; said switching relay, contacts, wipers and all of said meansco-operating in response to said series of received impulses to 31 stepto said pre-determined group of outlets the set of wipers having accessthereto, and to switch through a connection to said last-mentioned setof wipers.

9. In a telephone system, a calling line having an impulsing device, aswitch including a relay, a circuit arrangement and wipers, means forextending said calling line to said switch, means for operating andrestoring said relay, means whereby said second-mentioned means iscontrolled by an impulse from said pulsing device received over saidcalling line, means for connecting said wipers to said circuitarrangement, means whereby said fourth-mentioned means is operatedresponsive to said operation and restoration of said relay, means forconnecting said calling line through said circuit arrangement to saidwipers, means for disconnecting said calling line from said wipers,means for again operating and restoring said relay, means whereby saideighth-mentioned means is controlled by said disconnection of saidcalling line, means for disconnecting said wipers from said circuitarrangement, means whereby said last-mentioned means is operatedresponsive to the second operation and restoration of said relay.

10. In a telephone system, a calling line having a dial, a switchincorporating a relay, a circuit arrangement and Wipers normallydisconnected from said circuit arrangement, means for extending saidcalling line to said switch, means for causing two different operationsof said relay, means whereby said second-mentioned means is controlledby a digit dialed over said calling line, means for connecting saidwipers with said circuit arrangement, means whereby said fourthmentionedmeans is operated in response to said two different operations 01 saidrelay, means for connecting said calling line through said circuitarrangement to said wipers, means for disconnecting said calling linefrom said wipers, means for again causing said two different operationsof said relay, means whereby said last-mentioned means is controlled bysaid disconnection of said calling line, means for disconnecting saidwipers from said circuit arrangement, and means whereby saidlast-mentioned means is operated in response to said last two differentoperations of said relay.

11. In an automatic switch, a relay having an A and a B contact, meansfor operating said relay, means whereby said relay operating means isoperated responsive to the initiation of each impulse of a receivedseries of two impulses, means whereby said A contact is operated inresponse to each operation of said relay, means for restoring saidrelay, means whereby said relay restoring means is operated responsiveto the termination of each impulse in said series of impulses, meanswhereby said A contact is restored in response to each restoration ofsaid relay, means for operating and restoring said 13" contact, meansfor conditioning said B contact operating and restoring meanspreparatory to operating said"B contact, means whereby said conditioningmeans is controlled by the first operation of said relay, means wherebysaid conditioned B contact operating and restoring means is operated inresponse to the first restoration of said relay, thereby to operate saidB contact, means for causing a different conditioning of said B contactoperating and restoring means preparatory to restoring said B contact,means whereby said different conditioning means is controlled by thesecond operation of said relay, means whereby said differentlyconditioned B contact operating and restoring means is operated inresponse to the second restoration of the relay, thereby to restore saidB contacts.

12. In an automatic switch having a first and second set of wipers, afirst and second group of outlets accessible to said first and secondset of wipers respectively, an electromagnet, conductors, contacts onsaid electromagnet, said contacts normally connecting said first set ofwipers to said conductors, means for energizing and de-energizing saidelectromagnet, means whereby said first mentioned'means is controlled byeach impulse of a received series of impulses, means whereby saidcontacts are operated responsive to a first energization andde-energization of said electromagnet, circuit means whereby said firstset of wipers is disconnected from said conductors and said second setof wipers is connected to said conductors in response to each operationof said contacts, means whereby said contacts are restored responsive toa second energization and de-energization of said electromagnet, circuitmeans whereby said second set of wipers is disconnected from saidconductors and said first set of wipers is connected to said conductorsin response to each restoration of said contacts, means whereby saidcontacts are thereafter operated responsive to each succeedingodd-numbered energization and de-energizatio-n of said electromagnet,said first circuit means disconnecting said first set of wipers fromsaid conductors and reconnecting said second set of wipers to saidconductors upon each operation of the contacts, and means whereby saidcontacts are thereafter restored responsive to each succeedingevennumbered energization and de-energization of said electromagnet,said second circuit means again disconnecting said sec-0nd set of wipersfrom said conductors and again reconnecting said first set of wipers tosaid conductors upon each restoration of the contacts.

RUDOLPH FRANK STEHLIK.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,569,936 Land Jan. 19, 1926 1,849,694 Saunders Mar. 15, 19321,914,384 Richardson June 20, 1933 1,922,237 Escott Aug, 15, 19331,924,661 Stehlik Aug. 29, 1933 1,956,371 Christian Apr. 24, 19342,090,522 Sippel Aug. 17, 1937 2,289,896 Bakker July 14, 1942 2,294,907Hovland Sept. 8, 1942 2,416,086 Christian Feb. 18, 1947 2,416,109 LongFeb. 18, 1947 2,458,262 Grimes Jan. 4, 1949

